Actinobacillus actinomycetemcomitans has been strongly implicated as a primary periodontal pathogen in localized juvenile periodontitis(LJP). Recent evidence has suggested that, in patients with LJP and possibly refractory periodontitis, the primary IgG antibody response is directed against the endotoxin produced by this organism. Specifically, IgG antibodies are produced against the O-polysaccharide moiety of the LPS in Aa. However, the IgG generated is principally of the IgG2 subclass. This subclass typically exhibits poor opsonic antibody which may therefore minimize the protective nature of the immune response. One of the long term objectives of proposed studies is to develop a conjugated vaccine for LJP patients with world help generate protective antibodies that may benefit the LJP and/or RPP patient with respect to control of Aa infection.